Fire up the morph brush and set the following parameters.

Not definitive by any means but these are the ones that worked for me. For the knee change it to 'Loosen Fit' first and pull it away a bit.

Now run the brush over one of the stocking and it will shrink to the offset distance. You only have to do this for one leg as there is a mirror option. Simply mirror it from one stocking to the other.

Poser Pro 11, DAZ Studio 4.9